Ryuax is a droid sent by Esmeraude to capture Chibiusa for Prince Demande. She has a very elegant humanoid appearance and lives inside another dimension called the Cosmic Time Warp; a bleak, empty void in time. She appears to be the only living creature that dwells there. She appeared in episode 82 of Sailor Moon R. She can alter time to send her opponents' attacks back at them. She can also extend her finger nails into claws and use her hair as a weapon.

After scattering the Sailor Senshi, Tuxedo Mask, Luna, Artemis, and Chibiusa across the Time Warp, Esmeraude sent Ryuax to capture Chibiusa (deliberately forgetting to tell her to capture Sailor Moon, whom Demande has fallen in love with and ordered Esmeraude to bring to him). Ryuax disguised herself as Chibiusa' mother in an attempt to trick her but wasn't able to fool Chibiusa. Chibiusa fought Ryuax with a slingshot but was unable to damage her. The Sailor Senshi appeared and attacked her but their attacks were sent back at them. Sailor Mercury discovered that the flow of time is back to normal for a moment after the droid attacks. Chibiusa attacked the Ryuax, distracting her, and the Sailor Senshi combined their powers to blast five colorcoded energy beams (Sailor Planet Attack) at the Ryuax, killing her.